In the past, a catheter has been introduced into a blood vessel in order to examine or cure a heart disease or the like. To introduce such a catheter to a target site in a body, a guide wire is inserted into the catheter and a distal end of the guide wire is allowed to go ahead. The distal end of the guide wire is allowed to reach the target site and thereafter the catheter is guided to the target site.
In particular, in PCI (Percutaneous Coronary Intervention), while selecting a branch of a coronary artery under radiographic guidance, the distal end of the guide wire is allowed to reach a vascular narrowing portion as a target site and passed through it. Thereafter, an expansion catheter equipped with a balloon at a distal end is inserted along the guide wire and the balloon of the expansion catheter is located at the vascular narrowing portion. The balloon is expanded to push and widen the vascular narrowing portion to ensure blood flow. In this way, a treatment for angina or the like can be performed.
In such an treatment, to insert the guide wire from a femoral artery and advance it to an aorta, an aortic arc and a coronary artery, the guide wire requires the following: flexibility and restoring performance for following the shape of a blood vessel, indentation performance and torque transmissibility (generically referred to as “operability”) for reliably transmitting to a distal end force encountered when a proximal portion of the guide wire is pressed, anti-kink performance (anti-bending performance), etc.
To advance the guide wire from a branch portion of the coronary artery to a desired branch, shaping in which the distal end of the guide wire is shaped to conform to the shape of the branch portion is performed with fingers. Such work is called reshaping.
For example, if a guide wire is inserted into a peripheral side coronary artery, a conventional distal shape such as an angle-type or J-type preliminarily molded cannot select a desired branch. Because of this, the distal end of the guide wire is formed in advance into a desired shape for insertion in many cases. If such a shape still does not conform to the desired branch, the guide wire is once removed from the catheter and reshaped.
As the reshapeable guide wire, a guide wire is proposed that includes e.g. a superelastic core material; a reshaping member secured to the vicinity of the distal end of the core material; and a coil obtained by helically forming a raw-wire and installed to cover the distal end of the core material and the reshaping member. (See e.g. patent document 1.) In this guide wire, also the coil is secured to the vicinity of the distal end of the core material together with the reshaping member. The guide wire described above is such that the distal end can be reshaped by the function of the reshaping member.
The reshaping member disclosed in patent document 1 is formed rectangular in transverse section; therefore, it is called a shaping ribbon. This shaping ribbon is formed of a material tending to be plastically deformed, such as stainless steel or the like.
However, the guide wire provided with such a shaping ribbon has a large difference between the bendability (bending rigidity) of the superelastic core material and the bendability (bending rigidity) of the shaping ribbon, which results in that the joint portion between both causes stress resulting from the difference of the bendability (bending rigidity). If the stress concentrates, the shaping ribbon is bent in the vicinity of the joint portion so that the function as the guide wire is impaired.
The guide wire described in patent document 1 is provided with a coil obtained by helically forming a raw-wire. The raw-wire is different in pitch between both sides of the joint portion mentioned above. However, in the coil, the pitch of the raw-wire is rough on the distal end side of the joint portion but fine on the proximal end side thereof. Therefore, the difference in the pitch of the raw-wire in the coil described above acts to further increase the stress resulting from the difference in the bendability (bending rigidity) between the core material and the shaping ribbon described above.
Because of this, the guide wire described in patent document 1 has a concern that because of bending, the shaping ribbon does not sufficiently function in a bent blood vessel.    Patent Document 1: Japanese Patent Laid-open No. Hei 4-292174